The purpose of this investigation was to compare the effect of body posture on gastric emptying measurements of radiolabeled meals. Eight healthy male subjects were studied on four separate days. During each study subjects were fed a standardized meal of beef stew labeled with technetium-99m sulfur colloid, and orange juice. Measurements of solid-phase gastric emptying rates were obtained by a gamma camera. Subjects were studied in the lying, sitting, standing, or combined sitting-standing postures. The results demonstrated that the lying position significantly slowed gastric emptying compared to all other positions. Conversely, a decrease in emptying times of 51% and 35% occurred in the combined sitting-standing position compared to the lying and sitting position. These results support a marked effect of body posture on the radionuclide measurement of gastric emptying.